The present invention relates to a wafer basket for containing a plurality of semiconductor wafers, and more particularly it relates to such a wafer basket equipped with an improved device for locking and unlocking the lid.
Semiconductor wafers to be made into substrates for semiconductor electronic devices are obtained by thinly slicing a single crystal ingot of a semiconductor material such as silicon in a direction substantially perpendicular to the axis of the ingot. Thus, a semiconductor wafer is thin and fragile; besides, it need be kept clean from any contamination. Hence, transportation of wafers requires a great care and caution.
For this reason, it was a conventionally adopted practice to place wafers in a row at regular intervals in a wafer basket and transport the wafers in the basket. FIGS. 10-12 show an example of such wafer basket (ref. Japanese Utility Model Application Kokai 63-166948).
A wafer basket is a box-like rack for containing semiconductor wafers, and is commonly molded integrally of a synthetic resin. FIG. 10 is a side view of the wafer basket, FIG. 11 is a front view of the wafer basket, and FIG. 12 is an enlarged cross section taken on line D--D of FIG. 11; this wafer basket consists of an outer box 101 and an inner box 102; a plurality of wafers W are each received in the respective grooves defined by and between partition ribs 102b which form the pleated side walls 102a, 102a of the inner box 102, which are facing each other; therefore, the wafers are placed in a row perpendicular to the sheet of FIG. 10 at regular intervals in the inner box 102. The wafer basket is also a vehicle means for transporting the wafers W it contains.
The outer box 101 consists of a main body 101A and a top lid 101B, and when an inner box 102 containing wafers W is inserted in the main body 101A of the outer box, a top lid 101B is fitted on the upper rim of the main body 101A to thereby close the wafer basket.
Now, the locking device which works when the top lid 101B is fitted over the main body 101A of the outer box 101 will be described. The top lid 101B is provided with a pair of resilient hooks 116, 116 one on the front side and the other on the rear side (only the front one is shown in FIG. 11) in a manner such that they oppose each other and extend from the lower periphery of the top lid 101B downward; the hooks 116 are horizontally elongated along the box side and near either end of each hook is made an engagement hole 116a.
Engagement pins 122 are formed to extend more or less horizontally from the upper rim portion of the main body 101A of the outer box 101 at locations which coincide with the engagement holes 116a of the hook 116. When the top lid 101B is fitted on the upper rim of the main body 101A of the outer box 101, as shown in FIG. 12, the engagement holes 116a made in the hooks 116 of the top lid 101B allow the corresponding engagement pins 122 of the main body 101A of the outer box 101 to enter them to thereby automatically engage with the corresponding engagement pins 122 with the result that the top lid 101B is locked to the main body 101A of the outer box 101.
Incidentally, in the above conventional locking device, to unlock and open the top lid 101B, it was necessary to disengage the engagement holes 116a from the engagement pins 122 by pulling the hooks 116 of the top lid 101B outwardly (in the direction indicated by the arrow in FIG. 12), as shown in two-dot chain line.